* [CVE-2026-90381][LOW] wifi: mt76: fix handling channel context with different bands in mt76_switch_vif_chanctx() [ Upstream
@ 2026-09-18 7:58 21% AL-KERNEL
0 siblings, 0 replies; 1+ results
From: AL-KERNEL @ 2026-09-18 7:58 UTC (permalink / raw)
To: kernel-cve
CVE: CVE-2026-90381
Priority: LOW
AL-KERNEL base severity: LOW
KPANIC flag: NO
Patch: wifi: mt76: fix handling channel context with different bands in mt76_switch_vif_chanctx() [ Upstream
Commit: 063169a2755abdcbe7698d98360336abb6bef414
Upstream patch: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=063169a2755abdcbe7698d98360336abb6bef414
Original CVE announcement: https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90381
Analysis date: Fri, 18 Sep 2026 03:58:03 -0400
ActionableScore: 1
ActionableScore lower bound: unknown
Actionable bucket: Ordinary Moderate
Manual review required: NO
Summary:
No one-sentence report phrase was found.
======================================================================
ABOUT THIS REPORT
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90381 is available here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90381
The original announcement does not normally provide a security severity
estimate, CVSS assessment, or enough information to determine whether the
reported kernel bug represents a practically relevant security issue.
This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin. It combines
an autonomous classifier with LLM-assisted technical analysis and a
separate ActionableScore mechanism.
The purpose of this report is to prioritize Linux kernel CVEs before
manual review, identify cases that require prompt investigation, and
support automatic closure of issues that are unlikely to have meaningful
security impact.
Published priority for this report: LOW
Manual review required: NO
A detailed explanation of the methodology and priority rules is included
at the end of this message.
======================================================================
AL-KERNEL CLASSIFICATION RESULT
======================================================================
CVE-2026-90381 LOW https://www.kernelcve.org/list/?q=CVE-2026-90381 CHECK WITH IMPACT FROM ORIG NN MODERATE Maybe valid. Check manually. Hints by AL-KERNEL: The best (paranoid) CVSS is 'AV:A/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L';CWE-667;*CWE-664;CWE-703;Other CVSS 'AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L';BEST CVSS score: '2.6';DESCR 'mt76_switch_vif_chanctx could handle a batch of VIF channel context switches as if all entries used the same old context new context and radio band. When channel switches happen on different radios in a short time window, this can leave mt76 driver state inconsistent by updating the wrong PHY or assigning the wrong channel context to a VIF link. For the CVSS the PR:N is used only for the paranoid adjacent interpretation where an attacker may influence Wi-Fi channel switch behavior over the air, while reliable local triggering usually needs CAP_NET_ADMIN. The issue is not a proven memory corruption primitive and there is no direct evidence of information disclosure or privilege escalation. Impact is mainly denial of service or Wi-Fi disruption with low availability impact. NO MANUAL CHECK REQUIRED COULD BE AUTOCLOSED unless the affected product exposes untrusted adjacent Wi-Fi channel switch control as a security boundary.';NO MANUAL CHECK; ,and ActionableScore result is Ordinary Moderate (with actual score 1) YES REMOTE INIT NETWORK DECREASED_TO_MODERATE_REGULAR_FROM_MODERATE7_BASED_ON_GUESSCVSS DECREASED_TO_LOW_FROM_MODERATE_BASED_ON_ACTIONABLESCORELESSTHAN3 YES NO checked
======================================================================
ACTIONABLESCORE ANALYSIS
======================================================================
ActionableScore=1
PrimitiveClass=CLASS_C
RealUAF=NO
HostAdminRequired=UNKNOWN
NamespaceScopedPrivilege=NO
ImportantCandidate=NO
ManualReview=NO
AutoDowngradeAllowed=YES
1. ActionableScore
* Raw conservative score: 1
* Conservative score: 1. No floor or cap applied.
* Raw paranoid score: 1
* Paranoid score: 1. No floor or cap applied.
* Final recommended bucket: **Ordinary Moderate**::
2. Signal breakdown
* +1. Weak invalid active driver state. The old code treated a batch of VIF channel context switches as if all entries shared the same old context, new context, PHY, and band, which could update the wrong PHY or assign the wrong channel context.
* +0. No real UAF, stale reference, double release, refcount mutation, OOB access, arbitrary write, or controlled kernel memory corruption is established.
* +0. No reliable kernel crash is demonstrated. The supported impact is Wi-Fi disruption or inconsistent mt76 driver state.
* +0. No direct remote or network packet processing reachability is established. Adjacent Wi-Fi influence over channel switching is possible in some deployments but not proven as a complete attacker-controlled trigger.
* +0. No local unprivileged trigger is established. Reliable configuration of multi-radio channel context switching likely involves privileged Wi-Fi control, but the complete privilege boundary is not fully shown.
* +0. No race penalty applied. The commit says short timeframe, but it does not establish a narrow or hard-to-win timing race.
* +0. No rare hardware penalty applied. This is hardware-specific mt76 Wi-Fi driver code, but special rare physical access is not established.
* +0. C/I not awarded. There is no disclosure, unauthorized modification of protected data, credential impact, or security-boundary bypass.
3. Reachability analysis
The visible trigger is a channel context switch operation involving multiple VIF entries on different radios or bands. Controlled triggering is most plausibly through local Wi-Fi configuration or management paths, commonly requiring CAP_NET_ADMIN or an equivalent Wi-Fi control role, but the supplied patch does not fully prove host-admin-equivalent privilege for the complete path. Namespace-scoped reachability is not established because the affected object is a physical mt76 Wi-Fi device and no complete namespace-contained trigger chain is shown. Adjacent over-the-air influence is not excluded, for example through channel switch behavior, but the patch does not establish that an untrusted nearby transmitter can reliably create the exact multi-radio mixed-band switch batch. No special boot option or unusual kernel configuration is shown beyond having affected mt76 hardware and multi-channel PHY support.
4. Primitive and severity interpretation
The primitive is an invalid state or wrong-object-selection bug in channel context handling. It is not a memory lifetime primitive. It is not active-object UAF, fixed stale storage, double release, RCU mismatch, or controlled corruption. The demonstrated consequence is incorrect mt76 PHY/channel-context state, which may cause Wi-Fi malfunction or limited denial of service for the affected device. Speculative consequences such as kernel memory corruption, privilege escalation, or information disclosure are not supported by the patch. ImportantCandidate is NO because there is no meaningful unresolved corruption, ownership, authorization, or lifetime primitive. AutoDowngradeAllowed is YES because the issue appears to be a functional driver-state correctness bug with low security impact.
5. One-sentence report phrase
mt76_switch_vif_chanctx could mishandle batched VIF channel context switches across different radio bands, causing incorrect PHY or channel context assignment and possible Wi-Fi disruption, but the patch does not establish memory corruption, privilege escalation, or direct remote exploitability.
6. Manual review recommendation
NO MANUAL CHECK NEEDED
Reason: no concrete kernel corruption, UAF, authorization bypass, or strong DoS primitive is established, and the likely impact is limited Wi-Fi disruption or device-local inconsistent state.
7. Call-site confidence
Call-site confidence: medium
======================================================================
UPSTREAM PATCH SUMMARY
======================================================================
Patch: wifi: mt76: fix handling channel context with different bands in mt76_switch_vif_chanctx() [ Upstream
Commit: 063169a2755abdcbe7698d98360336abb6bef414
Upstream URL: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=063169a2755abdcbe7698d98360336abb6bef414
Changed files:
drivers/net/wireless/mediatek/mt76/channel.c
Diff excerpt:
Not included in this email. See the upstream URL for the full patch.
Full patch:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=063169a2755abdcbe7698d98360336abb6bef414
======================================================================
DETAILED REPORT METHODOLOGY
======================================================================
The original Linux kernel CVE announcement for CVE-2026-90381 can be found here:
https://lore.kernel.org/linux-cve-announce/?q=CVE-2026-90381
The original CVE announcement normally does not include a security-level
estimate. In particular, it may not contain a CVSS assessment, an impact
level, or enough information to determine whether the reported bug is a
practically relevant security issue. One purpose of this parallel CVE list
is to provide that missing technical and prioritization information.
The original goal of the AL-KERNEL project was to prioritize Linux kernel
CVE analysis automatically before manual review. The system can also help
identify non-security issues that may be suitable for automatic closure.
This report was generated by AL-KERNEL, an AI-assisted Linux kernel
vulnerability analysis system developed by Alexander Larkin.
The first analysis stage combines an autonomous classifier with additional
LLM-based analysis. The autonomous classifier runs locally on a CPU and is
based on a backpropagation neural network. Together, these mechanisms
produce a technical vulnerability description, identify likely weakness
types, estimate CVSS severity, and provide input for ActionableScore.
Two CVSS estimates are retained because incomplete kernel vulnerability
information often permits more than one defensible interpretation:
Conservative CVSS vector: AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L
The Best / paranoid CVSS vector: AV:A/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:L
The Best / paranoid CVSS score: 2.6
The conservative vector represents a lower-impact interpretation.
The Best/paranoid vector intentionally represents a plausible upper-bound
interpretation and should not automatically be treated as demonstrated
real-world impact.
CVSS may also need to be adjusted for a particular Linux deployment,
because actual reachability, privileges, enabled kernel configuration,
hardware, namespaces, exposed device nodes, and other environmental
conditions can differ significantly between systems.
A separate ActionableScore mechanism evaluates practical remediation
urgency. Its analysis may include reachability, attack prerequisites,
subsystem exposure, memory-corruption characteristics, denial-of-service
reliability, and possible confidentiality, integrity, or
privilege-escalation impact.
Conservative ActionableScore: unknown
Paranoid ActionableScore: 1
The final base severity is taken directly from the second tab-separated
field of the AL-KERNEL classification result. ActionableScore does not
replace or independently override that final AL-KERNEL decision, and
if ActionableScore adjusted impact level of ALKERNEL, then you would see
self-readable flags above like INCREASED_TO_HIGH_BASED_ON_ACTIONABLESCOREHIGHEREQTHAN7.
For an AL-KERNEL result of MODERATE, this report uses the following
additional presentation split:
ActionableScore below 5 -> MODERATE REGULAR
ActionableScore 5 or more -> MODERATE 7.0
The distinction between MODERATE REGULAR and MODERATE 7.0 makes it
possible to identify Moderate issues that should receive manual analysis
and fixes before lower-priority MODERATE REGULAR issues. In many cases,
MODERATE REGULAR fixes may wait for a later rebase or routine update.
There is one override in which MODERATE REGULAR becomes MODERATE 7.0
even when the ActionableScore is below 5. When the AL-KERNEL result
contains the KPANIC flag, a MODERATE result is always presented as
MODERATE 7.0. The KPANIC flag selected with few regexps without
usage of AI at all, so it helps to detect cases when Kernel Crash happens
and similar (to filter False-Negative results from the LLM usage).
KPANIC indicates that a reliable kernel crash, kernel panic, or similarly
serious kernel availability impact was identified by the classification
workflow.
AL-KERNEL base severity for this report: LOW
KPANIC detected for this report: NO
Published priority for this report (same as in Subject): LOW
These results are intended to support engineering triage. They are
machine-generated estimates, and cases marked for manual review should
be validated by a human security engineer before final disposition.
For more info read docs linked from here: https://kernelcve.org/
(and you can submit you own patch there to generate such a report
for non-existant CVE-id yet).
Note that in many cases this AI tool selects higher severity, than
real is (means you can expect Importants instead of Moderate 7.0 or
Moderates 7.0 instead of regular Moderates). If you see such cases,
please use reply email interface to add additional manual analyses
info to this particular CVE.
And please, please, let me know when you see Lows instead of Importants
or Important instead of Low (because particular for such cases I
need to tune this AI tool to make it better for this one and next similar).
My contact email for such notifications is [email protected] (and both
send reply to CVE record itself too and see "reply" button below for howto reply).
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